To provide better protection against injury to the occupants of a motor vehicle, generally an automobile, in cases of lateral collisions, it is known to provide a girder or beam which can have any of a number of cross sectional shapes, e.g. a tubular, I-profile or some other structural shape, as a reinforcement or stiffening element in the doors and/or side walls of the vehicle. Attention may be directed in this regard to U.S. Pat. No. 4,915,442 which issued 10 Apr. 1990.
Such girders are fastened on door frame parts or the vehicle body beams of the vehicle and brace the thin outer sheet metal elements against impact-type loads applied from the exterior.
In the case of an accident, especially a lateral collision, the girder deforms inwardly together with the outer sheet metal element and transfers the force of the collision to the structural elements of the body and the chassis, i.e. the body structure or the door frame.
To fulfill modern-date safety standards, at the beginning of deformation the strength of the girder and its resistance to impact should approximate the load carrying capacity of the door frame or the structural elements upon which the girder is mounted. The greater the resistance to deformation initially, the greater will be the deformation work which is transferred to and taken up by the structural elements carrying the girder and, therefore, the vehicle body.
During the deformation, however, it is not advantageous to allow the resistance to deformation to increase except to a slight extent, to ensure that the support or frame parts carrying the girder will not become overloaded and subjected to massive deformation.
It is thus important to be able to provide a control deformation of such a girder and especially a deformation which will prevent overloading of the parts of the vehicle body supporting same.